<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>simpleCalculator</title>
</head>
<body>
<form action="calculator.php" method="post">
    数字1：<input type="text" name="num1">
    <select name="option" id="">
        <option value="+">+</option>
        <option value="-">-</option>
        <option value="*">x</option>
        <option value="/">÷</option>
        <option value="**">x²</option>
    </select>
    数字2：<input type="text" name="num2">
    <input type="submit" value="计算">
</form>
</body>
</html>